"He is a guy that has been coming big for us in the playoffs," said Bruins defenseman Torey Krug. "So not having him for the rest of that game definitely hurt us. "

Julien declined to discuss his replacement options if Horton is unable to play. No available forward has played for the Bruins in the postseason.

Horton has a league-best plus 22 rating in the playoffs. He played about 22 1/2 minutes in Game 1 before skating to the dressing room after tangling with Chicago's Niklas Hjalmarsson in front of the net on a power play in the first overtime.

Tyler Seguin took his place on the Bruins' No. 1 line with David Krejci and Milan Lucic.

Horton left a April 20 game after a fight with the Pittsburgh Penguins' Jarome Iginla and missed the final five regular-season games with an upper-body injury, thought to be a shoulder. He returned for the playoff opener and has 18 points in 17 games, including three game-winning goals.

If Horton sits out Game 2, it will be the second consecutive time he has missed games in a Stanley Cup Final. He suffered a playoff-ending concussion in Game 3 of the 2011 Final on a hit that led to a suspension for Vancouver Canucks defenseman Aaron Rome.

Game 6 in Boston: Chicago Blackhawks center Andrew Shaw (65) covers his face with a towel as he is checked on by defenseman Michal Rozsival (32) and a trainer after being hit with a puck during the first period.
Greg M. Cooper, USA TODAY Sports

Game 5 in Chicago: Blackhawks 3, Bruins 1 -- Patrick Kane, center, and the Blackhawks defended home ice and took a 3-2 series lead on the Bruins in Game 5. Kane scored two goals for Chicago.
Scott Stewart, USA TODAY Sports

Game 5 in Chicago: Blackhawks 3, Bruins 1 -- Bruins defenseman Dennis Seidenberg (44) and Blackhawks wing Brandon Saad (20) keep their eyes on the puck as it bounces through the air during the second period.
Scott Stewart, USA TODAY Sports

Game 2 in Chicago: Bruins 2, Blackhawks 1 (OT) -- Daniel Paille (20) sent the Stanley Cup Final back to Boston tied at a game apiece, scoring the winning goal at 13:48 of overtime.
Rob Grabowski, USA TODAY Sports

Game 1 in Chicago: Blackhawks 4, Bruins 3 (3OT) -- The 2013 Stanley Cup Final got off to an incredible and entertaining start with a triple-overtime classic. Andrew Shaw, center, ended the fifth-longest game in Cup Final history when he deflected in the game-winning goal at 12:08 of the third extra period.
Scott Stewart, USA TODAY Sports

Game 1 in Chicago: Blackhawks 4, Bruins 3 (3OT) -- Blackhawks wing Bryan Bickell (29) and Bruins wing Chris Kelly (23) keep their eyes on the puck as it bounces through the air during the first overtime.
Scott Stewart, USA TODAY Sports